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University of Florida researcher Aldo Rincon holds out the lower jaw of Aguascalieta panamaensis, a newly described species of ancient camel. The 20 million-year-old fossil specimen was recovered from the Las Cascadas formation in Panama.

MIAMI — Researchers scratching in the sediment during the historic expansion of the Panama Canal say they have discovered the fossils of a small camel with a long snout that roamed the tropical rainforests of the isthmus some 20 million years ago.

The ancient camel had no hump, and one of the two species found appeared to stand only about 2 feet tall (60 centimeters tall), scientists reported in a recently published article in the Journal of Vertebrate Paleontology.

University of Florida researcher Aldo Rincon, a doctoral student in geology, discovered the fossils during the canal's widening to accommodate hulking new cargo ships that will soon ply the waterway. He and a group of other scientists from Panama, the United States and the Smithsonian Tropical Research Institute also reported finding fossils of ancient marlins, turtles and horses.

"We never expected to find a camel there," said Smithsonian scientist Carlos Jaramillo, co-author of the journal article. "It's really, really a surprise."

Unlike contemporary camels, these had crocodile-like teeth.

"It was like a little dog," Jaramillo added.

Scientists believe the camels, Aguascalientia panamaensis and Aguascalientia minuta, may have used the sharp teeth as they chomped on lush foliage and fruit.

The find is raising questions about just how long ago the isthmus was created. The discovery of a mammal fossil also could help scientists better understand what happened when present-day North and South America were finally connected.

Construction in progress
Geologists and paleontologists have essentially been traveling in the footprint of construction workers who are completing a five-year expansion of the Panama Canal. The $5.2 billion project will allow larger, modern container ships and cruise liners to traverse the canal — doubling the waterway's capacity by 2015.

The construction work is providing a unique opportunity for researchers to excavate and preserve fossils buried in sediment that are normally hard to uncover beneath the extensive tropical foliage.

Though a relatively small country, Panama carries great scientific importance because it serves as the land bridge connecting North and South America. When that gateway between the continents was created, there was a global sea change: the Pacific and Atlantic oceans were cut off from one another, and a great interchange of animals began, leading some species into extinction and others to adapt.

Researchers have long thought the isthmus was created 3.5 million years ago, but now that scientists have discovered a camel species living in the area about 17 million years earlier, that hypothesis is being questioned.

"It's pretty unusual to find camel remains that age at that place," said John Kricher, a biology professor at Wheaton College in Massachusetts who specializes in tropical ecology and is not affiliated with the project. "It certainly is a significant find by any measure. And it rewrites something of mammalian deep time history."

Mammalian mystery
Plant species are believed to have spread between continents about 45 million years ago, and some animals such as crocodiles and turtles at about 20 million years ago. Mammals, however, didn't travel over until considerably later — between 1.5 million and 3 million years ago, scientists estimate. Why they didn't is still somewhat of a mystery.

Unfortunately, there are big gaps in the ancient fossil record in Panama. Jaramillo said there are no fossils dating between 1 and 4 million years old there.

"Most of Panama was already up," Jaramillo said. "It was like a mountain, so erosion was very intense. No sediment was left during that time period."

Bruce Patterson, curator of mammals at the Field Museum of Natural History in Chicago, said the camel finding shows Panama was clearly part of North America, because the species didn't make it into South America until much later.

"In a sense it really enlarges the ecological envelop of the camel radiation to have them living in tropical rainforests and browsing," Patterson said.

Originated in Florida and Texas
The camels are believed to have originated in Florida and Texas and then evolved as they moved southward.

By studying the teeth of the camels, scientists can determine what they ate. While the molars of today's camels tend to be flat from grazing on grasses, the camels of Panama had more ridged teeth, indicating they were browsers that ate a variety of plant life. The species is now extinct in the Americas but researchers say they likely evolved into the llamas and guanacos now seen in the Andes.

"Probably the camels we see today in Peru, Bolivia and Ecuador, they come from these camels that were living in Panama," Jaramillo said.

Rincon discovered the fossils in 2008 and uncovered pieces of a jaw belonging to one animal over the next two years. He said Wednesday that the remains had been covered in volcanic ash over time and were well preserved.

"It's something like Pompeii," he said, referring to the Roman city that was preserved when buried by a volcanic eruption thousands of years ago.

Crocodilian teeth
Rincon traveled back to the university in Gainesville, Fla., and began putting the pieces together. Many of the remains had a green coating from the volcanic ash that he had to carefully remove. Soon he realized he had nearly a complete jaw and that it belonged to a camel.

"I was excited," the 33-year-old researcher said, adding he was surprised by their unusual teeth. "They have kind of crocodilian teeth. I'm still trying to understand" that.

In all, fossils from about five camels have been found. Four of the recovered jaws belong to the larger species, which bear many similarities but are different in size. The taller of the two likely stood no more than three feet tall.

Rincon and scientists from the U.S. and Panama are continuing to work under a grant from the National Science Foundation.

The researchers start each day early to avoid the sun's strongest rays and get called to excavate sites as workers expanding the canal come across new discoveries. After about four years of field work, they have uncovered numerous trees, plants, frogs, rodents and crocodiles dating millions of years.

But camels hadn't been discovered anywhere in Panama before.

"It's something you don't even dream about," Jaramillo said.

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